Chemical vapor deposition and atomic layer deposition are critical manufacturing steps in semiconductor fabrication. In particular, the deposition of oxide films is an important component in the fabrication of integrated circuits. More specifically, it has long been known that thermal processing must typically be employed if gaps are required to be filled in an integrated circuit construction. In this regard, the materials TEOS and Ozone are usually employed to fabricate undoped, thermal oxide films. Heretofore, chemical vapor deposition chambers of traditional designs have included a showerhead chemical distribution system. The prior art shows several varieties of these showerheads. For example, there is a premixing showerhead and a post mixing showerhead. In premixing showerheads all chemicals are premixed in the showerhead before entering the reaction zone where they are subsequently deposited on the semiconductor work piece.
The advantage of the prior art premixing showerheads is that the chemical reactants are substantially fully mixed so that the resulting chemical composition can be uniformly deposited across the surface of the semiconductor work piece. In these premixing showerheads, the temperature of the showerhead needs to be closely controlled in order to minimize potential chemical reactions. In the situation where chemicals such as TEOS and Ozone are employed for thermal oxide deposition, an increase in the showerhead temperature typically reduces the likelihood of liquid condensation if a liquid chemical is used, and will thereafter favor the delivery of TEOS. However, higher temperatures experienced within the showerhead typically reduces the Ozone concentration since the half-life time of this chemical is strongly temperature dependent.
Still further, it has long been recognized that when TEOS and ozone are premixed in a showerhead, polymerization and particle formation may result. This production of particles within the showerhead can potentially deteriorate the resulting gap fill performance of the resulting oxide film in an integrated circuit construction, if these polymeric particles are deposited on the semiconductor work piece surface.
To address the deficiencies noted in the prior art premixing showerheads, a number of post-mixing showerheads have been proposed. Still further, other designs of showerheads have been suggested in the prior art. For example, the prior art is replete with numerous post-mixing showerhead designs, and the Office's attention is directed to U.S. Pat. Nos. 5,624,498; 5,963,834; 6,148,761; 6,086,677; 6,089,184; 6,245,192; 6,302,964; 6,415,736; 6,435,428 and U.S. Publication Nos. US2005/0263248 and US2006/0021703. While these prior art devices and teachings have worked with varying degrees of success, those skilled in the art have long sought after a showerhead which reliably allows the delivery of a plurality of reactant chemicals such as TEOS and Ozone to a semiconductor work piece while substantially avoiding the shortcomings of the prior art which includes the formation of various particles which may be deposited on the semiconductor work piece or within the showerhead itself.
Therefore, a gas distribution assembly for use in a semiconductor work piece processing reactor is the subject matter of the present application.